In this video, I take a look at the latest neutral density filters for the GoPro Hero8 and newly-released GoPro Hero9.

Last spring, I bought the Standard Day 4 Pack from Freewell for my GoPro Hero8. It included the Metal Protective Cage and four filters — a polarizer and ND filters: 4, 8, and 16. As I illustrated in the previous review, the 16 was not strong enough to use on a bright, sunny day. In the interim, I made a Heath Robinson version of an ND 32 by gaffer taping a 4 and 8 together to achieve a 5 stop reduction … not really a long-term solution

I contacted Freewell to ask about stronger filters. They assured me that those were in the works, but like so many other goods that have been in short supply this year, Covid-19 had shut down their Chinese manufacturing facility.

I explain the use case for ND filters in the video above. For video, ND filters reduce the amount of light entering the camera, enabling the videographer to maintain the 180 degree rule — for, say 24 frames-per-second* we should use a shutter speed double the frame rate = 1/48 (or as close as possible, depending on what your camera allows). Often, this means your image will be overexposed so we must use filters to control the exposure.

This assumes setting up manual controls (and a custom preset) in the GoPro camera.

For stills, we most often want to extend exposure time — minutes to hours — to achieve blur effects in elements like running water and moving clouds (aren’t clouds always moving?). For stills we’ll use ND filters up to and beyond 1000 (optical density 3.0 or minus 10 stops) I didn’t buy the 10 stop filter as I don’t use the GoPro for stills. I have the equivalents for my Nikon full frame cameras (seen in this video).

Finally, I take the new filters for a drive in the field.

*24 FPS is accepted as the standard used to achieve a “cinematic” look in video. Moving objects are suitably blurred and results have less of the clinical appearance of faster shutter speeds typical of default settings in action cameras.